Biochips measure the concentration or the presence of biomolecules (for example DNA, proteins) in biological samples. A particularly innovative type of biochip is configured so that from the introduction of the sample to the measurement results, all steps for sample preparation and detection are carried out inside a closed unit of the biochip. Such biochips are also referred to as “lab-on-a-chip”.
The measurement processes in such a “lab-on-a-chip” may be very complex and comprise a multiplicity of sample preparation steps which precede the actual detection of the intended analyte, for example separation, enrichment, filtering, cell lysis or PCR. These may involve both mechanical and biochemical preparation steps.
Reaction substances which are needed in the course of the sample preparation or the detection either are supplied to the microfluidic system of the biochip from storage containers in the external reader, or they are prepackaged ready for use in storage chambers of the biochip, so-called reservoirs. In order to improve the durability and storability of the biochip, particularly biochemical reaction substances such as proteins and enzymes are often stored in dried form.
In the past, generally only the concentration of the intended analyte is measured in the sensor part of the biochip. If this measurement is faulty, no further measured quantity is available which could provide information about the cause of the measurement error, or which would even permit correction of the measurement error.